Breast Cancer in Transgender Patients Following Medical and Surgical Intervention

Background Current breast cancer (BCa) screening guidance does not adequately address transgender populations despite differences in hormone exposure and post-surgical anatomy. Methods Using the TriNetX network (2003–2023), transgender adults were identified using ICD-10 codes and grouped by sex assigned at birth and intervention: no intervention (NI), hormone therapy (HT ≥1 year), or HT with surgery (SX). BCa was defined as ≥2 diagnoses of malignant breast neoplasm (ICD-10 C50.x). Results Among 33,775 transgender women, 12 (0.036%) developed BCa. HT alone was not associated with increased odds of BCa diagnosis. Among 44,117 transgender men, 37 (0.084%) developed BCa. Combined HT and chest surgery was associated with higher odds of BCa diagnosis compared with NI. Older age at diagnosis and Black race were significant predictors in both cohorts. Conclusions Hormone therapy alone was not associated with increased breast cancer risk in transgender individuals. However, residual breast tissue after chest surgery may contribute to persistent risk in transgender men, supporting individualized screening strategies based on intervention type, age, and race. Micro Abstract Breast cancer screening guidance for transgender populations remains limited. Using the TriNetX database, we analyzed 77,000+ transgender individuals stratified by hormone therapy and surgery. Hormone therapy alone was not associated with increased breast cancer diagnosis; transgender men undergoing chest surgery had higher odds of diagnosis. These findings support individualized screening strategies incorporating intervention type, age, and demographic risk factors.